Watering Grass Seed at Night – Bad for Your Lawn?

Believe it or not, the timing of watering your lawn matters, and this is especially true when watering grass seed or a new lawn.  If you want to have a healthy, luscious lawn, you need to pay attention to ensure you are watering your lawn at the optimal time (and watering grass seed at night is not a good idea).

In short, the best time to water your lawn is in the morning, specifically before 10AM. 

The morning brings cooler temperatures than during the day, and the lack of heavy winds or breezes ensures all of the condensation and water from your sprinklers goes directly into your lawn and does not evaporate into the air.  This creates less waste, conserves water, and gives your new grass seed the water it needs to thrive and grow during the heat of the day.

Another reason for watering your lawn in the morning is because watering your grass in the morning will make the temperature on your lawn cooler all day, therefore putting less stress on your new grass.

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Why Watering Grass Seed at Night is a Bad Idea

You may think that watering your lawn at night will have the same effect on your grass seed and new grass as watering it in the morning. But that’s not the case, regardless if you’re starting a new lawn from scratch, patching bare spots with seed, or overseeding your lawn.

Watering you grass seed at night is not as good for your new lawn as watering it in the morning.

Below I outline some differences between watering your grass seed at night versus in the morning:

• Temperature – The temperature between watering your grass in the morning and watering your grass at night is almost indiscernible.  Both times will ensure that evaporation is kept to a minimum, allowing the most water to penetrate into your grass. The difference is that watering your lawn in the evening gives disease and fungus the opportunity to thrive and ruin your lawn.
• Wind – Again, similar to the temperature argument, the wind at night and the wind in the early morning are very similar (low).  This will not affect your grass seed if you choose to water in the evening.
• Protecting Against the Sun – Here is where watering in the morning is better for your lawn than watering at night.  The water on the grass helps to keep the grass and soil cool during the day, putting less strain on your seedlings when direct sunlight beats down. Watering grass seed at night can create mold or fungus which will quickly destroy your lawn.

What if You Don’t Have Time in the Morning and Have to Water Your Grass Seedlings at Night?

If watering your lawn in the morning is impossible for you because of your work schedule, or for some other reason, I suggest watering your lawn in the late afternoon. 

The late afternoon brings cooler temperatures than during the day, and adding water to your lawn at this time will give your grass time to dry before night descends, which can help prevent disease.

Again, I want to warn you that keeping your lawn too wet during the night will actually encourage the growth of fungus and make your lawn more susceptible to disease. While watering your lawn in the late afternoon will give the water enough time to evaporate before the sun completely goes down, you miss out on the benefits of morning watering, which is the ideal time.

Remember: watering your lawn at night actually encourages fungus growth and makes your lawn more unhealthy than if you water in the morning or if you water in the late afternoon.

My recommendation is to buy an inexpensive timer that will attach to your spigot and the hose that runs to your sprinklers, so you can water your grass seed at the perfect time every day.

What the Experts Say About When to Water

We strive to make sure all of our recommendations are backed by experts in the field. If you’d like to learn more you can read the following articles from credentialed horticulturists and turfgrass specialists.

I highlighted the most pertinent parts from these three resources to save you time:

• According to Doug Soldat and John Steir of the University of Wisconsin Extension, “It is generally best to water your lawn early in the morning when water is less likely to evaporate quickly.” They add that while evaporation is also slow at night, “watering at night increases the possibility of disease because the grass leaves will stay wet for many hours.”
• According to Debra Ricigliano, a Maryland Certified Professional Horticulturist at the University of Maryland Extension Home and Garden Information Center (HGIC), “It is best to water earlier in the day so leaf blades do not remain wet overnight.”
• According to Clark Throssel and Zac Reicher, Turfgrass Specialists at the Purdue University Turfgrass Science Program, “The ideal time to irrigate a lawn is from 4:00 to 8:00 a.m.” They explain that “at this time water pressure is usually the highest, there is little distortion of the watering pattern by wind, and the amount of water lost to evaporation is negligible.” They add that “a potential problem of watering in the early evening hours may be greater incidence of disease.”